Chrome Mobile DevTools - Mobile Debugging Tools
Charles Proxy - HTTP proxy / HTTP monitor / Reverse Proxy
HttpWatch - HttpWatch: The ultimate HTTP Sniffer for Chrome, IE and iOS
HTTP Toolkit - Beautiful, cross-platform & open-source tools to debug, test & build with HTTP(S). One-click setup for browsers, servers, Android, CLI tools, scripts and more.
Flipboard FLEX - At Flipboard, we place a high value on tools that speed up and improve the development process.
Weer - A HTTP protocol debugger with Chrome DevTools frontend interface